An audio interface (such as a headphone jack) of a conventional audio signal sending device (such as a mobile communication terminal) or an audio interface of a conventional audio interface receiving device (such as a headphone) is generally a four-section interface, where a pin 1 and a pin 2 are audio pins, namely a left-channel pin and a right-channel pin. As a pin 3 and a pin 4 have different functions in different audio interfaces, however, there are two types of audio interfaces. As one type, the pin 3 is a microphone pin (MIC pin) and the pin 4 is a ground pin (GND pin). As the other type, the pin 3 is a GND pin, and the pin 4 is a MIC pin.
As audio interfaces have the above different types, when an audio interface of an audio signal sending device (such as a mobile communication terminal) mismatches with an audio interface of an audio signal receiving device (such as a earphone or a headphone), the audio signal sending device and the audio signal receiving device can neither communicate with each other via the MIC pin of the audio interface, nor transmit audio signals between each other normally using the audio pins (a left-channel pin and a right channel-pin) of the audio interface.
Thus, an audio interface self-adaption device that can adapt to audio signal send devices (such as mobile communication terminals) having different audio interfaces is required.